Conventional data communication receivers utilize many types of antennas for receiving signals having specific frequencies. Typically, antenna size and shape varies with both the frequency of the signals the antenna is to receive and the size and shape of the data communication receiver which houses the antenna. For instance, in many low frequency applications, the antenna takes the form of a wire connected to the receiver. In VHF and UHF bands, antennas are often shaped such that an electrical loop is formed by the antenna. In each case, however, the antenna must not only function electrically, but also physically fit into the data communication receiver.
As data communication receivers have become smaller and more complex, the space available for accommodating an antenna has decreased. One solution to this problem is to reduce the size of the antenna. This cannot always be done, however, without adversely affecting the electrical performance of the data communication receiver. A further solution to this problem, then, is to change the shape, rather than the size, of the antenna.
Along these lines, one conventional data communication receiver is designed such that the antenna is embedded within the housing. As a result, the antenna is held by the housing and no fasteners are necessary to secure the antenna. Thus, space within the housing that would normally be consumed by antenna fasteners, such as screws or clips, may be utilized to accommodate other mechanical and electrical components. The amount of additional space provided by this method, however, is minimal because fasteners are generally relatively small compared to other components utilized by the data communication receiver.
Another conventional data communication receiver, a card type receiver, actually employs the antenna as a portion of the housing. The antenna is formed from two conductive plates, one of which is used as a back cover of the data communication receiver and one of which is used as front cover of the data communication receiver. The plates are held apart by a frame defining the sides of the data communication receiver. Typically, the plates are secured to the frame by a plurality of screws which also electrically couple the two plates. In this manner, space for accommodating the antenna is provided by eliminating the areas of the housing which would normally form the front and back covers. Therefore, the interior of the data communication receiver may be filled with components other than the antenna, a feature that is especially useful in card type receivers, in which space is at a premium.
The use of the screws, however, to secure and electrically couple the antenna plates can create problems, both mechanical and electrical. For instance, the threads of the screws may easily become deformed or worn during assembly of the data communication receiver if the force used to tighten the screws is too great. As a result, the data communication receiver may sometimes be difficult or impossible to disassemble for repair purposes. Conversely, proper electrical performance of the data communication receiver is dependent upon the degree to which each screw is tightened. If, for example, the torque applied to each screw is insufficient, i.e., the screws are not properly tightened, the increase in contact resistance between the two plates may degrade the electrical performance.
Thus, what is needed is an improved method for electrically coupling two antenna plates in a card type receiver. Furthermore, the coupling method should not cause variations in the contact resistance, and therefore variations in the electrical performance, of the antenna.